Natural, aqueous extracts of Quillaja Saponaria, the Chilean Soap Bark Tree, contain several physiologically active triterpenoid saponins that display strong antiviral activity. An underexploited target for antivirals remains the viral receptor on the host cells. In preventing a virus from reaching its cellular receptor, the antiviral should not inadvertently activate the cell, as most receptors used by viruses are also functional cellular receptors being high-jacked by the virus. Most cells in a virus-infected individual will be uninfected and antivirals acting on these cells should not interfere with the normal functions of these cells if they are to be safe and effective. The central objective of this research is to develop and test the addition of small amounts of saponin to the water supply as a means to prevent or greatly reduce waterborne pathogens from infecting the host. We will use a mouse model of rotavirus induced diarrhea to test this hypothesis. We base this hypothesis on our demonstration that microgram amounts of extract, while exhibiting no cell cytotoxicity or direct virucidal activity, prevent seven viruses - vaccinia, herpes simplex 1, varicella zoster, HIV-1, HIV-2, rotavirus and reovirus from infecting their host cells. The saponin containing extract is GRAS listed and approved for use in foods and beverages for human consumption. The specific aims are to: 1) Demonstrate that aqueous extracts of Quillaja Saponaria at concentrations more than 1000-fold lower than concentrations exhibiting cell cytotoxicity in vitro, prevent rotavirus-induced diarrhea and cause no adverse side effects in the test animals. 2) Purify the Quillaja extract to isolate the antiviral activity. 3) Prepare undergraduate and graduate students for a career in health care research. The 3-year goals of this project include demonstrating that this extract is safe for use in mice and treatment of these animals results in no adverse effects, and demonstration that such treatment of these animals blocks virus infection of these animals. The long-term goals of this project include extending this antiviral to humans for testing and evaluation. Saponins offer some novel mechanisms of antiviral action, from interactions with viral envelopes leading to their destruction, interactions with host cell membranes leading to a loss of viral binding sites and coating of cells to prevent virus binding (3, 5, 28, 70, 76). Based on the preliminary results we hypothesize that a Quillaja extract can readily be added to the water supply to produce a product that is both virucidal, and able to block virus infection of the host. The extract is well suited to such an application as it is pH stable, is already approved as a food additive, is inexpensive, readily available and is soluble in water. [unreadable] [unreadable] [unreadable]